1. Field of the Invention
The present invention relates to a superconducting material and, in particular, to an organic superconducting material in the form of a thin film.
2. Description of the Prior Art
Since the discovery in 1979 of an organic material with metallic properties, known as TFT-TCNQ, considerable research has been carried out relating to the electrical conductivity of organic materials. Up to the present, dozens of types of organic superconductors have been developed. Of these, the highest temperature at which superconducting properties have been observed is only about 10 K. However, considerable attention is being paid to the fact that continuing research has been successful in sharply increasing the critical temperature, and to the fact that the key materials are readily synthesized.
This type of organic superconductor is often available in bulk form (aggregates of small crystals), and the electric and electronic industries found difficulty in application of the organic superconductor in bulk form in the electric and electronic fields, and are eagerly awaiting the appearance of these superconductors in the form of thin films.
At the present time, many different forms of thin films have been created experimentally, but up until now superconductors have not been available in these forms.
For example, trials have been run on a method by which organic superconducting materials are vaporized using a heater, then recrystallized on a film-forming surface. Many of the films formed using this method exhibit a structure which differs from that of the crystals of the starting material, or, a molecular composition which differs from that of the crystals of the starting material, so that they cannot be utilized in practice.
This is because an organic superconductor generally has a low sublimation point and a low heat resistance. Specifically, the organic superconductor decomposes immediately on vaporization and the molecular structure is destroyed.